Carrots he cooked for band (9)
I believe the answer is:
orchestra
'for band' is the definition.
(musical band)
'carrots he cooked' is the wordplay.
'cooked' indicates an anagram (letters cooked into a new form).
'carrots'+'he'='carrotshe'
'carrotshe' anagrammed gives 'ORCHESTRA'.
(Other definitions for orchestra that I've seen before include "Ensemble of players" , "Sort of stall" , "Carthorse (anag)" , "bandsmen?" , "Noted performers" .)